1. Field of the Invention
The invention relates to electronic semiconductor circuits, and more particularly to circuits which reduce power dissipation and semiconductor random access memory chips.
2. Description of the Prior Art MOSFETs (also called IGFETS) have been widely utilized, especially in integrated circuit form, to implement random access memories and other complex logic functions.
Power dissipation is frequently a problem in IGFET integrated circuit semiconductor chips because powder dissipation in such a chip raises the operating temperature, which may effect reliability of the MOSFETs on the chip. In MOS RAM (random access memory) integrated circuits, especially in dynamic RAMs, the main areas of power dissipation are in the column decode circuitry, row decode circuitry, sensing circuits, and input/output circuits. In memory systems constructed from MOS RAM chips packaged in conventional packages, a fairly large number of chips have their data output conductors coupled to a common data bus. However, only one chip at a time, referred to as the selected chip, can communicate with the common data bus. The remaining chips are said to be unselected. The chips incorporate circuitry which effectively electrically isolates their data output terminal from any low impedance to the respective semiconductor chip in response to a chip select input. The chip select input is frequently utilized to disable output and data input circuitry so that if the chip is unselected during a particular memory cycle, the data output driver has both its load MOSFET and its switch MOSFET turned off so that the data output conductor is essentially electrically floating, and so that the data input terminal is isolated from any storage cell during any memory cycle if the chip is unselected.